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I've really been struggling with this one. Followed manual and cycled power after unplugging, checked wiring at the service station-OK, actually ohmed out the entire wiring harness from main pca to the service station-OK, performed diagnostics test on SS primer motor--throws up 21.1:03, and replaced service station, TWICE, thought 1st could possibly be DOA-both SS's were probably OK, and probably even the old one was OK but maybe not--maybe it caused the failure of the main pca to begin with, don't know. I am really grabbing for anything now.

Had EMOD (main pca/psu), formatter checked out in test beds by whom I believe is a reputable technician. They checked out OK. But, I still think something is up with the main pca. (Could a bad formatter cause this error?):

This error 21.1:03 1st came up upon replacement of the main pca--old main pca was causing a hang at 58%--the formatter red light was flashing (#3 red light, I forget which one) that indicates "bad main pca". Replaced old main pca with "new" main pca WITH THE OLD SERVICE STATION (maybe the old SS blew the new main pca????, probably should have replaced both simultaneously???? but didn't know the SS was the culprit, and still don't know that) and immediately started getting system error 21.1:03 Failure moving the Primer Motor of the Service Station. I'm thinking the so-called new main pca is not getting the voltage or proper voltage to the primer motor--I see no movement of the primer motor at all during startup. Again, I've, since replacing the main pca, replaced the service station twice with new ones, again thought 1st SS might have been DOA.

To me, that seems to be "cause and effect". But I wouldn't bet $500 on it, maybe $50-100.

When I bought the main pca, I didn't fully realize that it wasn't sold separately but in an EMOD (main pca/psu), so that makes me a little suspect...why was it sold out of an EMOD? Maybe because it was actually bad and removed from an EMOD....

Also I have (heard these could maybe cause the error on same or similar models, other T series models):

--cleaned encoder strip, but appeared to be a spot at top on far right end, didn't seem to effect carriage movement.

--checked belt for proper alingment on gear and pulley-OK.

--checked rear carriage bushing for any damage--heard that could maybe cause the error, but looks OK.

--reset EEROM.

--updated firmware to latest.

--reseated formatter, many times.

--pulled all ink cartridges and printheads and installed as prompted-all OK. When I would do this with cartridges alone, it would even print out 1 print job but would throw up the error prior to the next job.

--performed diagnostic test on "primer motor", get so far and throws up 21.1:03.

Thanks for the response. I don't have an interconnect board as best I know. However, I strongly suspect that I got a bad new??? main pca [I don't think it was new...think an attempted refurb or just a used board, and again I should have bought a new EMOD (main pca & psu); I came across an alleged new main pca and bought it...shouldn't have. ....a reputable tech said the main pca, power supply unit PSU, and formatter were all good, but I question the main pca and maybe even the PSU.]. I'll check it out on the diagnostic tests/service tests for the scan axis and see what happens. It will be interesting to see what happens. Hoping to return the presently installed new??? main pca for a full refund or at least 20% restocking fee.

I've already obtained a new EMOD (main pca/psu), and will install it if necessary after I run tests and check other things out.

Kind of an aside...I'm thinking the formatter has nothing to do with this, but gosh, I wouldn't be surprised as it seems that so many things are interrelated.

Well, re. error 21.1:03 on T770, it turned out that the "new" main pca was bad (or maybe possibly the PSU was not providing the proper voltage. Don't know precisely. But I think it was the main pca--no 21.1:03 until the "new" replacement main pca was installed.). I replaced the emod with new emod and it works fine. Not sure why both main pca and PSU tested out fine for the technician; maybe not exhaustive testing; should've thrown up 21.1:03 for him too.

Lesson learned: I should not have bought a separate main pca which normally comes from the factory in an emod--main pca & power supply unit. I asked whether it was "new"; I was told "yes". I suspect the board was pulled from a bad emod and resold or repair was attempted unsuccessfully and was then resold or.... My mistake.